Nitrocarburizing

Ferritic Nitrocarburizing. This process is similar to carbonitriding, except that it is carried out in the temperature range of the stabiHty of ferrite and carbide (<723° C). Therefore hardening is not by martensite formation, but because of the formation of very hard carbonitrides. 

Austenitic Nitrocarburizing. This is similar to ferritic nitrocarburizing except that the temperature may extend into the austenite range. The case usually consists of hard carbonitride particles, and quenching to achieve hardening is not required. 

Austenitic nitrocarburizing, case hardening by, 76 211 Austenitic stainless steels, 23 305-306 Austenitic steels, 23 243-244, 301 Austenitization, 23 284—285 Australia... 

Plasma Impulse Coating Vapor Deposition (PICVD) process, 20 53 Plasma nitriding, 16 205 17 208 Plasma nitrocarburizing, case hardening by, 16 211... 

Figure 3. Residual stresses in automotive steel crown gears (a) net-shaped and submitted to nitrocarburation surface treatment machined by standard technology and submitted to (b) multi-frequency induction tempering, (c) quenching and nitriding, (d) case-hardening.

Nitrocarburized and Carbonitrided Light case depths with fair capacity for contact loads and good resistance to seizure... 

Figures 2 to 7 are partial isothermal sections corresponding to 700, 600, 590, 580, 550, and 500°C, respectively. These are calculated using the Gibbs energy functions reported by [1993Du]. They can be considered as the best representation of experimental data discussed in the section Introduction . Most notable feature of these diagrams is that (yFe) is present only in sections above 586°C, the temperature of flic eutectoid (yFe) e + 7 + (aFe). This agrees with most of the nitrocarburizing data. Note also fliat ((aFeyt-s) phase-field is present in sections close to 580°C, the most common nitrocarburizing temperature.

The phase equilibria in this system between 550°C and 600°C are of relevance to nitrocarburizing of steels. From the point of tribological performance, it is desirable to have a layer of carbonitride as the outermost... 

Som] Somers, M.A.J., Colijin, P.F., Sloof, W.G., Mittemeijer, E.J., Microstructural and Compositional Evolution of Iron Carbonitride Compound Layers During Salt Bath Nitrocarburizing , Z. Metallkd., 81(1), 33-43 (1990) (Experimental, Morphology, 28)... 

A STUDY ON THE IMPROVEMENT OF THE SERVICE LIFE OF SHAFT-BUSHING TRIBO-SYSTEMS BY PLASMA SULFUR NITROCARBURING PROCESS... 

To improve the service life of the shaft-bushing tribo system, the bushing was treated by plasma sulfur nitrocarburizing process. Before a plasma sulfur nitroearburizing, the specimens were... 

Table 2. The process conditions of the plasma sulfur nitrocarburizing...

Figure 4. High resolution TEM micrographs showing the cross section microstructure of the specimen prepared by plasma sulfur nitrocarburizing in H2S and CsHg gases.

Figure 5 is the XRD analysis on the surface area on the plasma sulfur nitrocarburized SCM440 steel. The XRD analysis showed that the compound layer of the plasma sulfur nitocarburized specimen consisted of c -FeroN and Y -Fe4N phases but the peak of FeS was not detected by XRD analysis. It is thought this was because the FeS layer was so thin to be analyzed by XRD or S was not formed the FeS during the plasma sulfur nitrocarburizing process. Also there were some reports that the FeS peak was not effectively detected by XRD because the Peaks for FeS phase were overlapped with those of other peaks [12, 13]. 

In this study, it is found that the newly developed S bushing prepared by plasma sulfur nitrocarburizing could replace the commercialized M bushing with salt bath nitriding and M0S2 coating. The important conclusions were made as follows. 

According to XRD analyses, a mixture of y and e nitride phase was observed in sulfur nitrocarburizing sample. But the formation of FeS layer was confirmed by XPS analyses. 

A Study on the Improvement of the Service Life of Shaft-Bushing Tribo-Systems by Plasma Sulfur Nitrocarburing Process... 

On commercial basis post nitrocarburizing oxidation treatments have been used to enhance the aesthetic properties of gaseous nitrocarburized components. However it is proved that these additional techniques improve the fatigue, wear and corrosion resistance of steel surface and can be successfully combined for this purpose. 

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